This invention relates to roof coverings and in particular to a roof system that diverts the flow of water in a pattern of flow that avoids roof areas that are susceptible to leakage or water damage.
Leaking roofs are a common problem for homeowners. Roof damage is often caused by leakage around openings such as skylights or leakage in high flow areas such as valleys between gables. Repairing such damage is often difficult, dangerous and expensive. Prior attempts to alleviate the effects of uncontrolled flow from roofs have met with limited success.
Common prior art roof systems develop problems because their drainage is totally uncontrolled. The flow of rain water from a roof having only a single gable and no penetrations such a skylight is very simple. Rain water flowing from such a simple roof takes a direct path down to the eaves and gutters of the roof. The flow of water from a roof having intersecting gables and openings such as sky lights is much more complex. The flow of water accumulates at gable intersections and around openings. A casual observation of the effects of the flow of water in nature quickly provides one with an impression of the erosive effects of uncontrolled water flow. Uncontrolled water flow upon roof structures has similar erosive effects. Rain water flowing off of a complex roof builds up in valleys between gables and runs in an uncontrolled fashion near parapet walls and chimneys and all along the edges of eaves. Provisions such as flashing for resisting the flow of water in high flow areas eventually fail under the pressure of repeated high volume energetic flow and expose materials that are susceptible to water damage. The transfer of water flowing from a complex roof to a gutter system is deficient because the gutter system must be adapted to accept uneven and uncontrolled flow. Prior roofing systems have not been designed to provide the optimal transfer of water from a roof to a gutter system, but rather, gutter systems have had to be adapted to accommodate the flow of water as dictated by the roof structure.
Even though a primary function of a roof is to protect a structure from the intrusion of water, the effective transfer of water from a prior art roof is not among the requirements that drives the design of a prior art roof. The pattern of drainage from a prior art roof is not optimized by design, but results from the architectural shape of the roof. The architectural shape of the roof is driven by esthetics and the internal geometry of the structure. Very little consideration is given to water flow when a prior art roof is designed. With a prior art roof, water simply follows an obvious downward path. A prior art roof will often have an accumulation of debris accumulation in the valleys between gables as well as debris in the gutter. This causes a moisture retention problem in the valleys and at the edges of eaves. Prior art roofing systems also require the periodic maintenance of flashing, parapet walls and chimneys where high volume energetic water flow often occurs. Consequently, prior art roofs fail in their main purpose of preventing the intrusion of the elements into a structure because they are not designed to manage the flow of rain water.
Prior art roof systems are also vulnerable to leaks during extreme weather. Snow and debris accumulate in the same areas that water tends to accumulate. Even if a roof is in good condition, problems often arise at the extremities of a roof system, especially in open valleys, parapet walls and the edges of eaves adjacent to clogged gutter systems.
One solution to the these problems would be to design roofs that have complex fluid dynamic shapes that are adapted to optimize the flow and transfer of rain water. No doubt this could make for a fascinating project for an architect and it is even possible that such a design project could produce fascinating and compelling shapes. However, it is unlikely that a practical solution gaining widespread acceptance in middle class residential neighborhoods would result from a theoretical project directed at creating fluid dynamic roof designs.
What is needed is a roofing shingle product that can be arranged in an array of shingles that will direct water away from vulnerable areas of a roof such as valleys between gables or penetrations and then also direct it to predetermined drainage areas where water flow will not cause damage. An array of such shingles would direct water in a predetermined pattern rather than being limited to having water to merely follow the slope of the roof. Such a roof shingle, for use in an array of shingles could be easy to manufacture and install.
The shingle system of present invention meets this need for improved drainage by providing a means to direct and control the flow of water as it flows down from a roof surface. In its simplest form, the roof system of the present invention includes rows of shingle elements having parallel, slanting lower edges that are aligned to divert the flow of water away from areas where high flow volumes are not desired toward areas where higher flow volumes will not cause harm. Because water flowing down a surface will tend to adhere to that surface, the water flowing down the surface of the shingle system of the present invention will tend to follow the slanting lower edges of the shingle elements in the direction of slant thereby providing a means for directing the flow of water on a roof.
A roof structure surface could be envisioned as being defined by set of contour lines that have constant elevation and a set of grade lines that are normal or perpendicular to the contour lines. As rain water flows down from a roof structure, it will have a direction of flow that is parallel to the grade lines and perpendicular to the contour lines of the roof. Stated more simply, on a roof surface, water will flow down hill.
However, the purpose of the present invention is to exploit a fluid flow phenomenon known as the xe2x80x9cCoanda Effectxe2x80x9d. Water flowing on a surface tends to adhere to that surface, and when flowing water encounters an edge, it resists flowing off of that edge. Accordingly, if water flowing down a surface encounters an edge that is oriented at an angle in relation to the contour line, the direction of flow will be altered to following the direction of the edge as the water follows the edge. So then, while standard roof shingles have bottom edges that are parallel to roof contour lines and normal to roof grade lines, a pattern of shingles of the present invention will have lower edges that are all aligned at an angle in relation to the contour line of the roof. Flowing rain water that encounters the angled lower edges of the shingles changes direction and follows those slanted lower edges.
In its preferred embodiment, the shingle system of the present invention includes shingles that each have a base portion that includes an upper head lap section and a lower butt lap section. The head lap section of each shingle is usually covered from above by an overlapping butt lap section of an adjacent shingle. The butt lap section of the shingle includes two layers of overlapping shingle elements having slanted lower edges. The slanting lower edges are substantially parallel to each other and slant at an angle relative to the contour lines of the roof. These slanted lower edges are also parallel with each other. Where the slanted lower edges terminate, the water continues on its angular path to follow the next slanted lower edge of the next shingle. By using shingles of the present invention, rain water on a roof can be directed at an angle relative to the grade line across the surface of the roof. Even limited applications of shingles of the present invention on only a portion of a roof can substantially direct water away from vulnerable areas. The invention shingle could be made of the same materials as other roof coverings such as aluminum, asphalt, wood, copper or composites such as cement composites or an other suitable roofin material.